Solenoid



W. A. RAY

SOLENOID Nov. 2, 193 7.

Filed July 27. 1936 IEEE INVENTOR.

BY l/Maw ATTORNEY.

Patented Nov. 2, 1937 PATENT OFFICE- SOLENOID William A. Ray, San Francisco, Calif., assig'nor to General Controls of California Application July 27,

5 Claims.

This invention relates to an electro-magnetic operator, commonly termed a solenoid. The present invention relates to an improved construction of a device generally disclosed in my copending application vSerial No. '635,386, flled' October 3, 1932. 'I'his actuator is useful in conjunction with valves of a small size, particularly those used in domestic heating installations. Since the actuator operates quietly upon alternating current, it is adapted particularly to the operation of valves in domestic heating operations for, upon current failure, the valve automatically closes, thus insuringthat fuel will not be supplied to a burner if the electric control circuit, in which the valve is included, should fail.

While the solenoid disclosed in the aforesaid application was successful, it was limited in power. The actuator of the present invention has been devised to provide a small actuator capable of supplying more power than that heretofore supplied by actuators of comparable size and input power requirements.

It is in general the broad object of the present invention to improve upon the construction ofV solenoid actuators to the end that the effective force upon the solenoid plunger is'materiallyincreased, although the electro-motive force utilized is substantially the same.

It is another object of the present invention to improve upon solenoid actuators to secure' a higher efficiency in operation upon alternating current accompanied by an absence of any humming or vibration.`

The invention includes other objects and feavtures of advantage, some of which, together with the foregoing, will be set forth at length hereinafter in the disclosure of the present preferred construction.

In the drawing accompanying and forming a part hereof:

vPigure 1 is a section taken through a solenoid structure involving the present preferred construction in which means are provided at opposite ends of the plunger for locating it.

Figure 2 is a cross section through another form of solenoid.v e Figure 3 is a Vcross section through the form of solenoid shown in Figure 2 with means for locating both ends of the plunger.

The actuator of the present invention is provided with a base 8 having a threaded extension l so that. the actuator can be suitably attached to a housing, such as that including a valve or `otherclevice to be operated. A non-magnetic Company, a corporation 1936, Serial No. 92,748

(CL F15-338) tube 8 of brass, monel, or the like, isrrolled over as at 9 against the base 6 at one end thereof to provide a circular seating surface for reasons which will presently appear. The tube 8 is extended through the base 8 and secured thereto as by soldering II. An insert I2 is secured as at I3 to the tube, the insert including an extension I4 threaded to receive a nut I6. A suitable housing, generally indicated at Il, is mounted upon and is secured in place upon the threaded extension I4 by means of thenut, this housing including an inlet I8 for attachment of a conduit including lead-in wires.

The extension I2 is made of non-magnetic material, but carries a ring II9 of magnetic material. This ring is grooved as at 20 and the tube 8 is rolled in to ilt this groove and to retain the magnetic ring in place. A-xnagnetic insert 2I is carried on the extension I2, the insert 2l projecting beyond the extension I2 and being formed at 22 to center the solenoid plunger generally indicated by numeral 24. The solenoid plunger is a composite structure, including an outer magnetic shell 23 or primary core approximating in size the ring I9. Mounted within and adjacent the upper end is a non-magnetic plug 30 providing a shading ring. Inserted within this plug is a Aimagnetic plug 26 providing a secondary core. -The magnetic plug 26 and non-magnetic plug 30 are -concentricall'y apertured longitudinally tol release-fluid. In addition, the shell 23 is apertured as at 25.

kSlid'ably mounted in the bottom portion of the solenoid plunger (Figures 1 and 3) is a stud 21. This stud is retained in place by a sleeve 28 of magnetic material screwed into the bottom of the sleeve 23. Sleeve 28 has a shoulder 29 thereon against which rests a light spring 3|. This spring urges a collar 32 upwardly to engage the annular surface 9 provided by the base 8 and the flared portion of the tube 8, as previously mentioned. i

The electromotive force is supplied by a coil 33 formed upon a spool fashioned of opposite insulating annular members Il usually of insulating material. The members 3l are joined by a spun over metal sleeve 34s. The coil is positioned between magnetic washers 35 and 38, these washers being mounted upon and including angular portions I1 extending along the tube 8.

In operation, the current ow through the coil reaches a maximum ow at the peak of the sine wave, and a minimum or zero flow at the` end of each half cycle. Actually there is a large v flow of ,current provided in one direction for a fraction of a second, followed by cessation of current ilow when the half cycle changes orthe curreverses. .This substantially constant force upon the plunger enables the hurnrning noise to be overcome. l

The present invention is concerned with the accurate centering of the plunger at all times, by means of the spring pressed collar t2 as well as the extension oi insert il at it engaging the insert it. At the same time two separate paths ior magnetic now are provided, one through the washers tb and tt and their extensions lil, through the magnetic ring l@ and the magnetic sleeve it. The other course includes the washers, their vextension till, the magnetic insert 2l and insert 2li. o

It is to be noted that the parts comprising the upper portion of the solenoid are substantially the saine size as those provided upon the movable portion so that the effect of the air gap between the two is materially reduced. At the saine time the solenoid plunger element and the magnetizing elements of the coil are so arranged as to reduce the effect of any air gap.

The present construction has enabled the efiective force of the solenoid to be materially in= creased. For example, utilizing the saine size coil, including the saine size wire and number of turns arranged in the same manner, the present construction enables an eective force oi forty ounces to be exerted by the solenoid, while the same coil, when utilized in the construction shown in the aforementioned copending application, was only effective to exercise a force ol l0 ounces. The material increase is obvious.

lit is to be noted that the main core provided by the sleeve is larger than the secondary core provided by insert 2t. lThis is important to avoid sticking when the current is cut oil, stop 2li also being of small mass and isolated so that it cannot provide enough residual magnetlsm to hold the plunger in its raised position. LThis isolation is secured by the non-magnetic support. While the stop is isolated when the current is o, the ring iS and extensions 3l ensure au adequate path for the flux.

The housing il? is of magnetic material and is mounted directly on the bottom washer so that magnetic flux is conductedbetween the twov washers and about the coil. Washer t@ is close to the housing and while an air gap exists beu tween the two, the housing is of large area to provide arnple magnetic conduction.

Sticking is one of the most objectionable ieae tures in -a device of this character and its avoidance is one or the primary objects hereof. rifhis is attained by providing a primary path through the plunger having a much larger capacity :tor conduction of the hun than that oi a secondary path, elements in the primary path being out oi contact with each other when the plunger is raised. The elements providing the secondary path are ot small mass relatively to those in the primary path.

"the present .invention provides means :for centering the plunger when it is raised, this means comprising the spring urged collar which centers on the surface t), and the stop- 2i and core 2t. LThese cooperate to maintain-the plunger in the magnetic center of the coil, the plunger, stop, collar and surface il being sym aooaico i mennen with respect to the megacamal axis of the plunger.

In Figure 2 I have shown a modied structure lin `which the solenoid plunger at 40 is made of a single piece, the upper portion being suitably apertured as at 4| to provide -for fluid release from the interior of the solenoid.'

This type of structure is subject to sticking and, generally, will stick more often than the structure heretofore described in connection with Figure 1. However, the tendency to stick is reduced by having the plunger relatively long.

In the structure shown in Figure 2 it is to be noted that I have indicated the housing il as engaging both the washers tt and 3b, thus providing a denite n'iagneticl` path between. these washers. The housing bi, usually of non-magnetic material, is mounted upon the top of the housing il and includes a connection 52 for wiring. A screw secures the housing 5i in place. This screw engages the magnetic stop i l. Mounted upon the magnetic stop and secured thereto is a non-magnetic washer tl which is secured to a non-magnetic tube lit. A washer 5l is secured on the magnetic stop 2i, vthis washer engaging a non-magnetic ringiitl which is supported upon washer tt.

The structure described is particularly useful' upon lower cycle alternating currents, particularly the 25 and 50 cycle. The structure disclosed in connection with Figure l can also be rendered useful upon the lower alternating currents by inserting a small magnetic rivet;` ti between the primary and secondary cores to provide a magnetic leakage path between these.

The magnetic material employed `is usually stainless steel, iron or the like while`the nonrnagnetlc--inaterial is brass or copper, a conductive material which is non-nlagnetic.l

In Figure 3 l have illustrated the centering rneans oi Figure l applied to the plunger type shown in lFigure 2.

l claim:

l. In a device of the character described, a solenoid plunger having a longitudinal anis, a coil concentric about said axis for moving said plunger including a passage therein `lor receiving said plunger, means for supporting said coil, stop means engageable by said plunger at one end of said passage and cooperating with said plunger to center one end of said plunger on said axis, a cone shaped collar carried by said plunger and slidable along said plunger to engage said support means to center the other end of said plunger, and a spring urging said collar along said plunger.

2. ln. a device of the character described, a coil; magnetic members positioned at each end o the coil; a plunger; said coil and said members having a passage therethrough for said plunger with each of said members ianged inwardly along said passage to provide annular magnetic members at each end oi said passage; a stop member including an outer magnetic stop inember positioned within one or said annular nientn bers and extending into-said passage, a non-magnetic stop member coentensive substantially with the inside oi said outer magnetic member, and an inner magnetic stop member enclosed by said nonmmagnetic member at its side portion and end away from said plunger, said outer member,

vsaid non-magnetic member and said inner meinber being joined together as a substantially unitary structure xed in position at one end of said passage; said plunger comprising a non magnetic plunger member carrying a magnetic plunger insert; therein for engaging said inner magnetic stop member, said plunger non-magnetic member enclosing said magnetic plunger insert substantially entirely at its side portion and end away from said stop member, and an outer magnetic plunger sleeve substantially surrounding said non-magnetic member and extending, when said stop member is engaged by said plunger insert, from closely adjacent said outer stop member to the annular member at the other end of said passage.

3. In a device of the character described, a coil; magnetic members positioned at each end of the coil; a plunger; said coil and said members having a passage therethrough for said plunger; a stop member including an outer magnetic stop member positioned at one end of said passage; a non-magnetic stop member coextensive substantially with the inside of said outer magnetic member, and an inner magnetic stop member enclosed by said non-magnetic member at its side portion and end away from said plunger, said outer member, said non-magnetic member and said inner member being joined together as a substantially unitary structure fixed in position at one end of said passage with said inner member extending beyond the other members of said stop; said plunger comprising a non-magnetic plunger member carrying a magnetic plunger insert therein for engaging said inner magnetic stop member within the confines of one of said non-magnetic members, said plunger non-magnetic member enclosing said magnetic plunger insert substantially entirely at its side portion and end away from said stop member, and an outer magnetic plunger sleeve substantially surrounding said non-magnetic member and extending, when said stop member is engaged by said plunger insert, from closely adjacent said outer stop member to the annular member at the other end of said passage.

4. In a device of the character described, a coil; magnetic members positioned at each end of the coil; a plunger; said coil and said members having a passage therethrough for said plunger with each of said members anged inwardly along said passage to provide annular magnetic members at each end of said passage; a stop member including an outer magnetic stop member positioned within one of said annular members and extending into said passage, a non-magnetic stop member coextensive substantially with the inside of said outer magnetic member, and an inner magnetic stop member enclosed by said nonmagnetic member at its side portion and end away from said plunger, said outer member, said non-magnetic member and said inner member being joined together as a substantially unitary structure fixed in position at one end of said passage; said plunger comprising a non-magnetic plunger member carrying a magnetic plunger insert therein for engaging said inner magnetic stop member, said plunger non-magnetic member enclosing said magnetic plunger insert substantially entirely at its side portion and end away from said stop member, and an outer magnetic plunger sleeve substantially surrounding said non-magnetic member and extending, when said stop member is engaged by said plunger insert, from closely adjacent said outer stop member to the annular member at the other end of said passage; a magnetic housing for said coil in engagement with themagnetic member at the end of the coil away from said stop; and means securing said housing on said stop non-magnetic member.

5. In a device of the character described, a coil; magnetic members positioned at each end of the coil; a plunger; said coil and said members having a passage therethrough for said plunger; a stop member including an outer magnetic stdp member positioned at one end of said passage; a non-magnetic stop member coextensive substantially with the inside of said outer magnetic member, and an inner magnetic stop member enclosed by said non-magnetic member at its side portion and end away from said plunger, said outer member, said non-magnetic member and said inner member being joined together as a substantially unitary structure xed in position at one end of said passage with said inner member extending beyond the other members of said stop; said plunger comprising a nonmagnetic plunger member carrying a magnetic plunger insert therein for engaging said inner magnetic `stop member Within the contines of one of said non-magnetic members, said plunger non-magnetic member enclosingtsaid magnetic plunger insert substantially entirely at its side portion and end away from said stop member, and an outer magnetic plunger sleeve substantially surrounding said non-magnetic member and extending, when said stop member is engaged by said plunger insert, from closely adjacent said outer stop member to the annular member at the other end of said passage; a magnetic housing for said coil in engagement with the magnetic member at the end of the coil away from said stop; and means securing said housing on said stop non-magnetic member.

WILLIAM A. RAY. 

